Automotive lamps generally employ light bulbs as their light source. These bulbs connect to the rest of the lamp assembly and receive their electrical power through lamp bulb sockets in the lamps. The design of these lamp bulb sockets vary but must at their most basic form contain means to secure the bulb in place in the socket, means to provide the bulb with the electrical power to function, and means to secure the lamp socket to the rest of the lamp assembly. While these are the minimum requirements for a lamp bulb socket, there are numerous other design characteristics that are desirable in modern lamp bulb sockets.
Lamp bulb sockets are typically one of two types. First, “axial” lamp bulb sockets include a housing body that extends directly behind the lamp. The housing body directs the wires connected to the lamp bulb socket away from the lamp bulb socket. In this manner, the wires are placed directly behind the lamp bulb socket and run parallel with an insertion axis 190 (See FIG. 1) along which the lamp bulb is inserted into the lamp bulb socket. Second, “right angle” lamp bulb sockets include a housing body that extends behind the lamp and then at a right angle away from the lamp. The “right angle” housing directs the wires connected to the lamp bulb socket away from the lamp bulb socket at a right angle to insertion axis 190.
The “axial” lamp bulb socket has the disadvantage of taking up a lot of space directly behind an automotive lamp, because the wires, terminals and the seals of the wires to the terminals all take up a great deal of space. A socket that takes up a lot of space directly behind an automotive lamp is undesirable because it limits design options for manufactures and prevents lamp sizes from being further reduced. In contrast, “right angle” lamp bulb sockets do not take up as much space directly behind an automotive lamp because they direct the wires at a ninety degree angle away from the lamp. However, while the right angle socket decreases the need for space directly behind the lamp socket, it increases the diameter space needed around the lamp to house the right angle socket. This too limits design options for automotive manufacturers. These limitations could be avoided with an automotive lamp bulb socket that occupies the same amount of space as a right angle socket directly behind the lamp but at the same time occupies the same amount of diameter space as an axial lamp socket around the lamp.
Another disadvantage with current lamp sockets is that they are manufactured with exteriors that permit either “axial” or “right angle” loading of the lamp bulb socket into the lamp assembly, but not both. As a result, two types of sockets must be produced by suppliers. This creates additional manufacturing expenses. These expenses could be eliminated or minimized by the use of a lamp bulb socket which is designed with an exterior that permits the same socket to be loaded either axially or at a right angle during lamp assembly. Such versatility in the exterior shape of the lamp bulb socket is just one of a number of desirable exterior design characteristics of lamp bulb sockets.
There are a number of additional qualities which are desirable on the exterior of a lamp bulb socket. First, the lamp bulb socket should be designed with exterior features which allow the socket to be easily aligned with the rest of the lamp assembly. This simplifies the process of attaching the lamp bulb socket to the lamp assembly and reduces manufacturing costs. Second, the exterior of the lamp bulb socket should contain a mechanism to securely lock the socket to the rest of the lamp assembly. This prevents the bulb socket from becoming loose inside the lamp assembly which could lead to the malfunction of the light source and the loss of illumination. Third, it is desirable for the exterior of the lamp bulb socket to contain a mechanism to prevent the over-rotation of the lamp bulb socket as it is being attached to the lamp assembly.
There are also qualities which would be desirable in the wiring of the lamp bulb socket. First, the lamp bulb socket should be designed to eliminate the pinching or misalignment of wires during the insertion of a light bulb into the socket. The pinching or misalignment of wires could prevent the proper connection of the bulb with the electrical terminals in the socket leading to a faulty electrical connection. The result is an inoperable light source. Second, the lamp bulb socket should be wired to eliminate as much wire splicing as possible. The elimination of wire splicing is desirable because it decreases the cost of manufacturing by reducing the number of necessary splicing operations, subsequent splice sealing operations, and components needed in constructing an automotive lighting system. Third, the electrical wiring used should be connected to the terminals of the lamp bulb socket by the most efficient method possible. It is also desirable that this connection be environmentally sealed to prevent the elements from degrading the connection and contributing to a premature failure of the light source. An environmental seal located between the lamp bulb socket and the lamp assembly is also required. This seal should be designed to minimize the force required for its installation in order to reduce the cost of manufacture.
In addition to the aforementioned desirable exterior qualities of a lamp bulb socket, the interior of the socket should also be designed with a number of beneficial qualities in mind. For example, the interior of the lamp bulb socket should be designed to help guide the lamp bulb into place. This is desirable for many reasons. First, properly guiding the bulb helps to prevent damage to the bulb's base during the installation of the bulb into the socket. Second, a design which guides the bulb into the proper position decreases the amount of force necessary for the insertion of the bulb, thus, decreasing the cost of manufacturing. Third, properly guiding the bulb into place decreases the possibility of terminal or lead wire damage.
Similarly, the interior of the lamp bulb socket and the terminal assembly should be designed to help guide the terminal assembly into place in order to promote the proper positioning and alignment of the terminal assembly in the lamp bulb socket. The design of the terminal should be one that minimizes the amount of force necessary for the insertion of the terminal assembly into the bulb socket in order to decrease the cost of manufacturing. Further, the design of the terminal should be one that promotes dimensional control of the points of contact between the terminal assembly and the bulb socket so that the terminal is easily inserted into the bulb socket and then held firmly in place so that the terminals do not wobble back and forth and cause a faulty electrical connection. It is important that the terminals are properly aligned and stabilized in the bulb socket so that a proper connection is formed and maintained with the bulb.
Another design quality that is desirable in lamp bulb sockets is the ability to accept bulbs of varying size. This gives the manufacturer flexibility in the manufacturing process. However, one resulting problem of using differing bulb sizes is the tendency for smaller bulbs to rock or wobble in the lamp bulb socket. Lamp bulb sockets should be designed to incorporate means to eliminate or minimize this wobbling. In addition to means for minimizing the wobbling of the bulb, another desirable feature of lamp bulb sockets is for the bulb to be firmly held in place once the bulb is inserted. The bulb must be secured such that the bulb will not disengage from the lamp bulb socket. If the bulb was not firmly held in place, the proper electrical connection may be lost resulting in a loss of illumination from the light source. Finally, steps should be taken to reduce the mass of the entire lamp bulb socket. Any reduction in the mass of the socket reduces the cost of shipping the final assembled sockets.
Currently, manufacturers produce a number of types of lamp bulb sockets. No design has successfully embodied the above-discussed beneficial qualities. For example, many current sockets continue to have exterior designs which permit only “axial” or “right angle” loading of the lamp bulb socket into the lamp assembly. Additionally, many sockets employ two-piece terminals which require assembly in the socket. By requiring additional assembly, these two-piece terminals are more likely to be misassembled. Two-piece terminals are also more prone to intermittent continuity problems and additional voltage drop. Thus, a lamp bulb socket employing one-piece terminals would be beneficial.
The lamp bulb socket terminals are usually connected to the power supply by wires which are crimped to the terminals. The terminals are then secured to the body of the socket by a piece called a terminal position assurance. This method of securing terminals requires additional pieces, is time consuming, and requires additional labor. This also increases costs and the rate of faulty connection. Additionally, the crimp method of connecting the wires to the terminals fails to provide a good environmental seal around the connection. As a result, these connections are subjected to the elements and corrode after time. Another disadvantage of most current lamp bulb socket designs is the use of a wiring configuration requiring multiple splices and several wire seals. This configuration adds unnecessarily to the assembly time required and the expense of manufacturing and adversely affects the quality of the harness.
The current methods of stabilizing the bulb known in the prior art can also be improved upon. Some prior art sockets use rigid bulb support members which cannot be used to control the wobble of smaller bulbs and still allow the use of larger bulbs. Further, some prior art sockets us a separate piece stabilization feature which has the shortcomings of increasing part count, manufacturing cost, assembly effort, and the possibility of the component becoming lost. Therefore, it would be desirable to find a new method of stabilizing the bulb.
Thus, a need exists for a lamp bulb socket which provides some or all of the desirable features discussed above while remaining relatively inexpensive and relatively simple to assemble.